In the conventional technology, the host (such as computer or mobile phone) issues a specific command to an electrically-connected data storage device (such as flash memory, etc.) according to the industry standard. Correspondingly, the data storage device replies the host about which tasks are ready for execution in response to the specific command. Then, the host issues a command to inform the data storage device to perform either a read or a write operation.
However, according to the conventional technology, although the data storage device can reply the host with a plurality of ready-for-execution tasks, the host cannot determine a better executing order of these ready-for-execution tasks. For example, the data storage device can efficiently execute a specified task. However, actually the host asks the data storage device to execute another task. Therefore, the data storage device must reallocate the system resource to complete the task. Thus, it is an important subject for the person in the art to make the host and the data storage device communicate with each other more efficiently and make the tasks ready for execution properly arranged.